Cummins 12V Engine Overhaul

1939dodge · 07-03-2011, 04:17 PM

Anyone around here completed an overhaul on a Cummins 12V? Do you have a manual, or did you just go from memory? I have never done this before so I need to know all of the torque specs etc so I do not end up blowing the thing up later. If someone has a manual that I could borrow or someone who has the time to help me that would be MUCH appreciated! I already have a full set of gaskets for the upper and lower engine.

While doing all of this work, are there inexpensive upgrades that should be done? The engine is powering my 1939 Dodge 1.5 ton truck, the truck is large and heavy. I want to be able to get around town, drive up the grapevine, and have reasonable fuel economy. I do not need 1,000HP, just enough to get around, get up to speed. I have the stock turbo, I am not sure if I can fit twins. Everything is stock, the engine had over 200K miles before it was pulled.

Thanks!

-Ryan

Water_Lover · 07-07-2011, 09:59 PM

With only 200k on the motor you dont really need to rebuild it. If your just doing it to start with a fresh motor I would have the cylinders honed put in a set of rings do all the bearings and I would put a Colt stage 3 cam in and some 50 hp injectors have the head gone through and if you have the time port the bowls and exhaust side of the head. You can find all the torque specs online a factory service manual runs 90 bucks

1939dodge · 07-07-2011, 10:18 PM

Yes I agree it is not mandatory to go through the engine now, but as you mentioned I am doing it so I have a fresh engine to start with. I am trying to limit the probability of blowing a head gasket, or something easy to fix now, not later.

That sounds like a good list of things to work on. Would you suggest me honing the cylinders or have someone do it? Does that mean I will have to increase the size of the pistons, or make other changes?

I have the Dodge manual, it has some specs I am not sure if that is enough information or if I get halfway through I will need more information. As I mentioned this will be my first time rebuilding any engine so sorry if some questions seem silly.

Thanks for your reply and advice!

-Ryan

jimmy421 · 07-08-2011, 01:43 AM

lol you dont need to rebuild it at 200 on the clock mine had 220 on it (and it was stock) then i modded it and 230 just had the cam go shaithouse when i tore it down and i should have just stuffed a cam back into it. you live by me kinda i think you can come look at all the parts and see how good they look if you want

1939dodge · 07-08-2011, 02:41 PM

Yes Jimmy, you live rather close to me, we met at a BBQ at your place. So you are trying to say that my idea to tear through the entire engine is a good one?? If so I figured it was better to take care of it now rather than wait for it to blow up later.

Looking at the Colt Cam, they sell it as a re-grind for around $350 or new for twice that... which way would you suggest??

jimmy421 · 07-08-2011, 06:38 PM

stage 3 new one and there are local dealers that you can pick one up for the same price

1939dodge · 07-08-2011, 09:47 PM

I was afraid that was the answer, because I am tight on cash, and there are a lot of things I still need.

SO I looked through my repair manual and found all of the specs and information to overhaul the engine... but there are areas where specialized tools are handy or required.

I know that at the end of the day it is not all that difficult to rebuild an engine (Time consuming yes), but I am sure I will have a stronger and better engine if I can have someone help me or stand behind me and tell me that I just fu@ked it up.

I have a huge air compressor, many air tools, but do not have the injector removal tool, feeler gauges or other special engine tools. I do have the gaskets already, but figure the tear down will take a little while before we can start re-building it.

Anyone up for helping me out, I have an espresso machiene in the shop, and a brewery behind my shop

Water_Lover · 07-08-2011, 11:39 PM

You dont need a injector removal tool just take off one of the injector hold down nuts then on the next injector take the nut almost all the way off put the other hold down nut ontop off it then use one of the dodge wheel lug nut they fit on the injector where the fuel line goes screw it down and the injector will get pulled out. A reground stage 2 cam would be fine if your not looking for alot of power. you can check the price at Source Automotive. Source Automotive

1939dodge · 07-09-2011, 12:06 AM

I have seen that method for injector removal, but not using the dodge nut, that is good to know it fits and works.

To me 500HP is not a lot of power, and that is about what I am going for eventually. The initial engine work will be just to make the inside parts and parts that are tough to get to later are all upgraded to handle the upgrades later. I understand some things require other upgrades, for example twins and big sticks go together.

Sounds like I will be replacing the springs at this time, and have seen spring compression tools. The injector tool was an example of one of the many things I will need and do not have.

Thanks